Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for recovering a data unit in a wireless local area network (WLAN).
Related Art
A user equipment (UE) supporting the IEEE 802.11a standard may have a transfer rate of up to 54 Mbps when data is transmitted through a 20 MHz channel band at a 5 GHz frequency band on the basis of orthogonal frequency division multiplexing (OFDM).
A UE supporting the IEEE 802.11n standard may have a transfer rate of up to 600 Mbps when data is transmitted through a 20 MHz or 40 MHz channel bandwidth at a 2.4 GHz or 5 GHz frequency band on the basis of multiple input multiple output (MIMO).
The IEEE 802.11ac standard aims to provide a throughput greater than or equal to 1 Gbps in a medium access control (MAC) service access point (SAP) layer. A wireless local area network (WLAN) system supporting the IEEE 802.11ac standard may also be referred to as a very high throughput (VHT) system. For the throughput greater than or equal to 1 Gbps in the MAC SAP layer, the VHT system may support a 80/160 MHz channel band and 8 spatial streams (or space time streams). If the VHT system supports the 160 MHz channel bandwidth, up to 8 spatial streams, 256 quadrature amplitude modulation (QAM), and a short Guard Interval (GI), then the UE supporting the VHT system may have a transfer rate of up to 6.9 Gbps when data is transmitted in a physical layer.
In order to satisfy the aforementioned throughput, a plurality of VHT STAs supporting the VHT system may transmit and receive data through the same channel simultaneously when communicating with an access point (AP). A VHT AP may transmit data simultaneously to the plurality of VHT STAs on the basis of space division multiple access (SDMA) or multiple user (MU)-MIMO. That is, data may be transmitted or received simultaneously between the plurality of VHT STAs and the VHT AP.
With the increase in a demand for high-definition multimedia transmission at present, an unlicensed frequency band is on an increasing trend. Further, it is not easy to ensure a contiguous 160 MHz channel bandwidth in the IEEE 802.11ac due to a channel bandwidth used by the legacy WLAN standard. Therefore, in the IEEE 802.11ac, a 160 MHz channel bandwidth in which non-contiguous channels are aggregated may be used.